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All COPO Chevelles were cut from the same basic cloth. Their reason for being was GM's ban on engines over 400 cid in midsize cars. Hot-bloods within Chevy itched to circumvent the rule. And with a handful of muscle-hungry dealers egging them on, Vince Piggins, Chevy's performance-products manager, found a way. He used the Central Office Production Order system, which normally filled special-equipment fleet orders, to factory-equip a run of Chevelles with L72 427-cid V-8s.

As in the COPO Camaro, the solid-lifter iron-block-and-head L72 used an aluminum manifold and an 800-cfm Holley four-barrel. Chevy rated it at 425 hp, but in calculating the car's stock drag class, the NHRA claimed a truer 450 hp. Chevelle's strongest regular four-speed or the Rock Crusher manual were offered, as was a fortified Turbo Hydra-matic. The strengthened 12-bolt Positraction axle had 4.10:1 cogs and the suspension was heavy-duty. Front discs -- standard on Super Sport Chevelles -- were a mandatory $64 option on COPO cars.

In fact, none of the 323 COPO Chevelles built were Super Sports. Instead, they were base coupes with a COPO option package that cost about $860, including $533 for the L72. Yenko put his trademark dress-ups on the 99 he ordered. But the balance that went to other dealers for individual sale looked deceptively docile.

From the SS they borrowed a black grille and tail panel, hood bulges, side stripes, and chrome exhaust tips. However, there was no performance ID on the body. The emblem-free L72 could pass for an aluminum-manifold 396. And the cabin was plain Malibu, though a few SS steering wheels were fitted. Even the standard rally wheels were similar to those on the base Malibu though they were in reality 15-inch units.